1. Field of the Invention
The invention relates to a control system for a vehicle that includes an engine and an automatic transmission gear device.
2. Description of Related Art
Japanese Patent Application Publication No. 2012-218670 (JP 2012-218670 A) discloses control for increasing an engine speed during a coast downshift such that a rotational speed of an input shaft of an automatic transmission gear device is changed to a synchronous rotational speed after shifting at an early stage during the coast downshift in a vehicle including an engine and the automatic transmission gear device. With this control, control for increasing the rotational speed of the input shaft of the automatic transmission gear device (hereinafter also referred to as “blipping control”) can be executed. Engine inertia (so-called engine brake) that acts on the input shaft of the automatic transmission gear device by downshifting can be reduced by this blipping control. Thus, a significant reduction of a vehicle speed during the coast downshift can be suppressed. The coast downshift is downshifting that is performed during coasting. The synchronous rotational speed after shifting is the rotational speed of the input shaft of the automatic transmission gear device after shifting and is determined from a transmission gear ratio after shifting and a rotational speed of an output shaft of the automatic transmission gear device.
However, in the case where the blipping control is not executed during the coast downshift due to some reason in the vehicle disclosed in JP 2012-218670 A, the engine inertia reduction action by the blipping control cannot be obtained. As a result, the vehicle speed is possibly reduced significantly during the coast downshift.